Salar de Uyuni is flat enough to calibrate satellites from space
Across roughly 10,582 square kilometres, the surface of Bolivia's Salar de Uyuni varies in height by less than a metre. That extreme flatness, a bright surface and clear skies make the world's largest salt flat a favourite target for calibrating satellite instruments, and after rain it becomes an enormous mirror.
The salt flat sits at 3,656 metres near the crest of the Andes in the Potosí Department. It formed as a sequence of Pleistocene lakes dried out: Lake Minchin, then Paleo Lake Tauca, which reached 140 metres deep, then Coipasa, whose disappearance left Lakes Poopó and Uru Uru and two salt deserts. Uyuni is about 100 times the size of the Bonneville Salt Flats, and its islands are the tops of old volcanoes drowned in Minchin's time. Satellites including Landsat-5 and Europe's Sentinel-1A have used it as a reference target.
Salar means salt flat in Spanish, and Uyuni comes from an Aymara word for an enclosure. In Aymara legend the surrounding mountains were giants; when Kusku left Tunupa for Kusina, her tears mingled with milk as she nursed her son and became the salt. Many locals say the place should be called Salar de Tunupa.
Beneath a crust up to a few metres thick lies brine rich in sodium, potassium, magnesium and lithium, the lithium at about 0.3 percent. Bolivia holds around 22 percent of the world's known lithium resources, mostly here, but foreign extraction met local opposition in the 1980s and 1990s, and the government has refused to hand the resource to foreign corporations. Of an estimated 10 billion tonnes of salt, under 25,000 tonnes are dug out each year.
Tourists stay in hotels built largely of salt blocks; the first, Palacio de Sal, went up between 1993 and 1995 but was dismantled in 2002 after its waste polluted the flat. Near Uyuni town lies a cemetery of trains abandoned when mining collapsed in the 1940s. Each November, Chilean, Andean and rare James's flamingos breed on the flat, feeding on brine shrimp.
Source: Salar de Uyuni
